1. Field of the invention
The present invention relates to an oil separating apparatus for an engine, particularly an engine used for a shaking machine such as a rammer.
2. Prior Art
Generally, there is an engine whose valve mechanism is lubricated by splashed oil, i.e., oil mist mixed with blow-by gas or oil in droplets splashed by a crank. In this type of engine, it is important to maintain a constant flow of blow-by gas within the rocker chamber and for that purpose this type of engine has an oil separating apparatus connected with the air intake system of the engine through a breather hose. In the oil separating apparatus, oil is separated from blow-by gas. Blow-by gas is sucked into the air intake system to be burned in the combustion chamber and oil is used for lubricating the valve mechanism.
In the prior art, this oil separating apparatus is accomplished by forming a breather chamber on the side wall of the cylinder block.
However, in order to complete the oil separation in the breather chamber, the breather chamber needs miscellaneous complicated techniques such as providing an oil shelter, changing the shape of the breather chamber variously, enlarging the volume of the breather chamber and the like.
Hence, many techniques have been proposed to raise oil separating efficiency of the breather chamber and to simplify its construction. For example, Japanese Published Utility Model Application No. Jitsu-Kou-Hei 6-6177 invented by the inventor of the present invention discloses an oil separating apparatus comprising an intake push rod chamber, an exhaust push rod chamber communicated with the intake push rod chamber through a rocker chamber, a breather passage communicated with one push rod chamber. The oil separating apparatus further comprises a breather port provided on the side wall of the other push rod chamber for communicating with a breather chamber and an oil separating device communicating both push rod chambers with the crank chamber through an oil return hole having a small diameter for repeating oil separation before blow-by gas enters the breather chamber.
In applying this technique to an engine for a shaking machine such as a rammer, since a significant amount of oil flows into the rocker chamber due to violent vibrations of the shaking machine, there is a possibility that the oil pan lacks oil and as a result sliding components of the engine have a lack of lubrication.
Further, the significant amount of oil flowing into the rocker chamber chokes passages and makes it difficult to process blow-by gas flow.
Further, in order to separate oil adequately from the blow-by gas containing a large amount of oil mist, a significantly large size of the breather chamber would be needed, exceeding a practicable level of size.